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.\" Author: Thomas E. Dickey
.\"
.\" $Id: legacy_coding.3x,v 1.28 2024/04/20 19:13:50 tom Exp $
.TH legacy_coding 3X 2024-04-20 "ncurses 6.5" "Library calls"
.SH NAME
\fB\%use_legacy_coding\fP \-
override \fIcurses\fR locale encoding checks
.SH SYNOPSIS
.nf
\fB#include <curses.h>
.PP
\fBint use_legacy_coding(int \fIlevel\fP);
.fi
.SH DESCRIPTION
.B \%use_legacy_coding
is an extension to the
.I curses
library.
It allows the caller to change the result of \fB\%unctrl\fP(3X),
suppressing \fI\%isprint\fP(3)-based checks within the library that
would normally cause nonprinting characters to be rendered in visible
form.
The alteration affects only eight-bit characters.
.PP
The
.I level
parameter controls the result.
.RS
.TP 5
.B 0
The library functions normally,
rendering nonprinting characters as described in \fB\%unctrl\fP(3X),
.TP
.B 1
the library ignores
.I \%isprint
for codes in the range 160-255.
.TP
.B 2
the library ignores
.I \%isprint
for codes in the range 128-255.
It also modifies the output of \fB\%unctrl\fP(3X),
showing codes in the range 128-159 as is.
.RE
.SH RETURN VALUE
If the screen has not been initialized,
or the
.I level
parameter is out of range,
.B \%use_legacy_coding
returns
.BR ERR .
Otherwise,
it returns the previous level:
.BR 0 ,
.BR 1 ,
or
.BR 2 .
.SH PORTABILITY
.B \%use_legacy_coding
is specific to
.IR \%ncurses .
It was not supported on Version 7, BSD or System V implementations.
Applications employing
.I \%ncurses
extensions should condition their use on the visibility of the
.B \%NCURSES_VERSION
preprocessor macro.
.SH AUTHORS
Thomas Dickey
(to support \fI\%lynx\fP(1)'s font-switching feature).
.SH SEE ALSO
\fB\%unctrl\fP(3X)
